Chemical reagents as probes: Application to fish protein gels and detection of a cysteine TGase in hake

Hydrogel based aptasensor for thrombin sensing by Resonance Rayleigh Scattering

In this research, a novel Resonance Rayleigh Scattering (RRS) aptasensor was developed for thrombin monitoring using in-situ synthesized and embedded Au nanoparticles (AuNPs) into poly vinyl alcohol -borax hydrogel (PBH). Thiolated-thrombin binding aptamer (thiolated-TBA) was attached to the surface of AuNPs embedded into PBH to design the PBH-aptasensor for thrombin detection (thiolated-TBA@AuNPs-PBH). To verify the characteristic and morphology of PBH nanocomposite, energy dispersive X-ray analysis, TEM, average particle size analizer and UV-Vis spectra were performed. The difference in RRS intensities in the absence and presence of thrombin was calculated and selected as the monitoring signal. Effect of different parameters on the RRS signal was investigated at excitation wavelength of 500 nm. Under the approved conditions, the linear detection range was validated over the concentration of 0.70 pM- 0.02 μM. The limit of detection based on 3S_b was 0.10 pM. The relative standard deviation for 5.6 pM and 3.6 nM were 4.0 and 2.7% (n = 10), respectively. The proposed aptasensor was successfully applied as an experimental model for thrombin detection in serum samples of healthy volunteers with acceptable results.

A sensitive and selective resonance Rayleigh scattering method for quick detection of avidin using affinity labeling Au nanoparticles

Avidin is a glycoprotein with antinutritional property, which should be limited in daily food. We developed an affinity biosensor system based on resonance Rayleigh scattering (RRS) and using affinity biotin labeling Au nanoparticles (AuNPs). This method was selective and sensitive for quick avidin detection due to the avidin-biotin affinitive interaction. Under optimal conditions, RRS intensity of biotin-AuNPs increase linearly with an increasing concentration of avidin from 5 to 160 ng/mL. The lower limit of detection was 0.59 ng/mL. This rapid and selective avidin detection method was used in synthetic samples and egg products with recoveries of between 102.97 and 107.92%, thereby demonstrating the feasible and practical application of this assay.